Just wanted to get some feedback regarding test pipes. So I have a stock M3 and I just want a cheap way to add power. So I'm thinking I'll add pulleys and a test pipe. But regarding the test pipe, can I run it with the stock x-pipe and stock axle-back? Also, what would I need to do regarding CEL lights? Will this set up drone and be overly loud? I saw the macht schnell post and I couldn't tell how much the sound changed over the dyno.

Also, is there any difference between different manufacturer test pipes? MS or others? Any particular you would recommend?